Molecular characterization of Clostridioides difficile isolated from older adults during prospective population-based active surveillance at nine hospitals in Tokyo, Japan, 2018-2020.

BACKGROUND

To characterize Clostridioides difficile isolates identified during a prospective multi-hospital population-based study of C. difficile infection (CDI).

METHODS

Between December 2018 and March 2020, inpatients ≥50 years of age with new-onset diarrhea in nine Tokyo hospitals were investigated for CDI. Stool specimens were screened by C. DIFF QUIK CHEK COMPLETE® and glutamate dehydrogenase (GDH) positive stools tested by Xpert® C. difficile/Epi PCR assay. PCR positive stools were tested by cytotoxicity neutralization assay to determine presence of functional toxin. GDH positive stools were also anaerobically cultured and whole genome sequences of C. difficile isolates were acquired.

RESULTS

Toxigenic C. difficile were isolated from 64 patients with CDI; 22 were RT018/356, 9 were RT369, 4 each were RT106 and RT002, 15 were other RTs, and 10 had an unknown RT. Four isolates were positive for binary toxin: one isolate each of RT027, RT078/126, RT080, and one unknown. In terms of the pathogenicity locus profile, 55 were tcdA+/tcdB+ and 9 were tcdA-/tcdB+. In terms of ST, 23 were ST17, nine were ST81, 31 were other STs, and one had a novel ST.

CONCLUSIONS

Consistent with prior studies, C. difficile isolates from patients with CDI represented diverse ribotypes with approximately one third of isolates RT018/356. Of note, one isolate each of RT027 and RT078/126 were identified, indicating these hypervirulent strains are present in hospitals in Japan. Public health interventions are needed to reduce the CDI burden in Japan.